The present invention relates generally to mammalian sulphamidase and to genetic sequences encoding same and to the use of these in the investigation, diagnosis and treatment of subjects suspected of or suffering from sulphamidase deficiency.
Bibliographic details of the publications referred to by author in this specification are collected at the end of the description. Sequence Identity Numbers (SEQ ID NOs.) for the nucleotide and amino acid sequences referred to in the specification are defined following the bibliography.
Throughout this specification, unless the context requires otherwise, the word xe2x80x9ccomprisexe2x80x9d, or variations such as xe2x80x9ccomprisesxe2x80x9d or xe2x80x9ccomprisingxe2x80x9d, will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.
The increasing sophistication of recombinant DNA technology is greatly facilitating the efficacy of many commercially important industries including areas of medical and pharmaceutical research and development. The ability to purify native proteins and subsequently clone genetic sequences encoding these proteins is an important first step in the development of a range of therapeutic and diagnostic procedures. However, practitioners have faced many difficulties in purifying target molecules to an extent sufficient to determine amino acid sequences to permit the development of oligonucleotide probes to assist in the cloning of genetic sequences encoding the target molecules.
Such difficulties have been particularly faced in the research and development of lysosomal enzymes. An important lysosomal enzyme is sulphamidase (sulphamate sulphohydrolase EC 3.10.11). This enzyme acts as a exosulphatase in lysosomes to hydrolyse the sulphate ester bond in 2-sulphaminoglucosamine residues present in heparan sulphate and heparin (Hopwood, 1989). A deficiency in this lysosomal hydrolase is responsible for the pathogenesis of Sanfilippo A (Mucopolysaccharidosis type IIIA [MPS-IIIA3]) syndrome (Kresse, 1973; Matalon and Dorfman, 1974). This is an autosomal recessive disorder of glycosaminoglycan catabolism leading to storage and excretion of excessive amounts of heparan sulphate and a variety of clinical phenotypes, but classically presenting with progressive mental retardation in conjunction with skeletal deformities (McKusick and Neufeld, 1983).
There is a need, therefore, to purify sulphamidase and to clone genetic sequences encoding same to permit development of a range of therapeutic and diagnostic procedures to assist in the diagnosis and treatment of disease conditions arising from sulphamidase deficiency.
One aspect of the invention provides an isolated nucleic acid molecule comprising a sequence of nucleotides which encodes or is complementary to a sequence which encodes a mammalian sulphamidase or fragment or derivative thereof.
Another aspect of the invention is directed to an isolated nucleic acid molecule having a nucleotide sequence substantially as set forth in SEQ ID NO:1 or having at least 40% similarity to all or part thereof.
Yet another aspect of the present invention contemplates a recombinant mammalian sulphamidase or fragment or derivative thereof.
Still yet another aspect of the present invention provides a nucleic acid molecule comprising a sequence of nucleotides encoding or complementary to a sequence encoding a polypeptide capable of hydrolysing the sulphate ester bond in 2-sulphaminoglucosamine residues and wherein said nucleotide sequence is capable of hybridising under low stringency conditions to the nucleotide sequence set forth in FIG. 2 (SEQ ID NO:1).
Still another aspect of the present invention is directed to a polypeptide comprising a sequence of amino acids corresponding to the amino sequence set forth in FIG. 2 (SEQ ID NO:2) or having at least 40% similarity thereto, more preferably at least 60% similarity thereto and still more preferably at least 80% or 85-90% similarity thereto or encoded by the nucleotide sequence set forth in FIG. 2 (SEQ ID NO:1) or a nucleotide sequence capable of hybridising to SEQ ID NO:1 under low, preferably under medium and more preferably under high stringent conditions.
In still yet another aspect of the present invention there is contemplated a method for treating a patient suffering from sulphamidase deficiency said method comprising administering to said patient an effective amount of recombinant mammalian sulphamidase or an active fragment or derivative thereof.
Another aspect of the present invention is directed to a pharmaceutical composition comprising a recombinant mammalian sulphamidase or an active fragment or derivative thereof and one or more pharmaceutically acceptable carriers and/or diluents.